Exponential growth in action

My long time running friend Ollie is a mathematician. He looks at the coronavirus pandemic though his particular expertise, readily warning that "my field is mathematics, NOT infectious diseases so if I err, I do not mind correction from a credentialed person. In fact, I encourage it." My emphasis added to his observations that follow.

1. Whether you get infected with COVID or not depends on many factors and is probabilistic; we can say "highly likely" or "not likely" but never "certainly".

Your likelihood of getting infected depends on your level of exposure; that is, the dose of the virus in a short amount of time. A few individual viruses are unlikely to infect you.

The dose you get depends on several things: how close you are to the infected person, how long, and what protective gear you have.

A mask basically mitigates the tiny droplets that transport the virus. It is most effective when worn by the infected person, as the virus density is highest on what comes out of their noses and mouths.

The mask is less effective, but still far more protective than nothing, on the non-infected person.  

Masks might not stop all of the virus from entering, but it does lower the dose by quite a bit thereby lowering the risk of infection. 

Yes, the mesh of the mask is larger than the size of the virus; what it does, though, is stop many of the water droplets that carry the virus. It is transportation interdiction.  

The strength of the dose of virus depends on the quality of the air circulation and how close you are to someone who is infected. (inverse square law, plus the droplets carrying the virus tend to drop.  

That is why social distancing is important. 

2. Yes, you can be totally irresponsible and probably get away with it; the probability of infection at any single incident is low. But repetition matters and eventually your luck may well run out. It is a bit like rolling a 360 sided dice; your chances of getting a single given number is low on any one roll, but if you roll it enough times, it will probably appear once ... though you can't say when. 

3. The virus doesn't care about your cause, your emotional needs, if it is "just family", that you prayed to your deity for protection, etc. It is all governed by ice cold laws of probability.  

4. Yes, the survival rate for most classes of individuals is high. But there are two other factors: 

1. Something like 10 percent of verified cases end up in the hospital and even those not hospitalized end up with ill effects for weeks to months afterward. 

2. Even worse, the virus can spread through you and infect someone who might be more prone to dying from it. That is exponential growth in action.

Nobody in the White House seems capable of this sort of scientific reflection, most especially the super-spreader-in-chief.